Hi Winfried,
The color manager can help to make things easier.
Please take a look on this algorithm:
- Open the jpeg2000 file
- Is that a 16 bit rgb image?
yes: input format = TYPE_RGB_16
- Is that a 16 bit gray image?
yes: input format = TYPE_GRAY_16
- Is that a 8 bits RGB image ?
yes: input format = TYPE_RGB_8
... and so one ...
- Is there any embedded profile?
yes: use it as input
no: use some predefined default profile, on depending on the
input space
output format = TYPE_BGR_8
- Do you have profile for your monitor?
yes: use it as output
no: use sRGB built-in
- Transform the image from input profile, input format to output
profile, output format
by calling cmsCreateTransform(), cmsDoTransform()
- Do a cleanup
That's all. And with such simple algorithm you have true color
management, and automatic
support of 8 and 16 bits for grayscale and RGB. You can also add support
for CMYK
or any other space just adding more input cases.
Regards
Marti.
szukw...@arcor.de wrote:
Marti wrote:
You are assuming that to do a color transform, both input and output
profiles have to be of same colorspace, but that's not true.
For the file:
file7.jp2: color-space(RGB ) profile-connection-space(XYZ )
16-bit e-sRGB JP2 restricted (to sRGB) profile)
I coded:
inprof = cmsOpenProfileFromMem(jp2_profile_buf, jp2_profile_len);
outprof = cmsCreate_sRGBProfile();
inspace = cmsGetPCS(inprof);
outspace = cmsGetColorSpace(outprof);
As the inspace is (XYZ ) and the outspace is (RGB ), I supposed I
I had to write:
transform = cmsCreateTransform(in_prof, TYPE_XYZ_16,
out_prof, TYPE_RGB_16, intent, 0);
But I got no transform. I had to change the code to:
transform = cmsCreateTransform(in_prof, TYPE_RGB_16,
out_prof, TYPE_RGB_16, intent, 0);
Incidentally, there is indeed a cmsCreate_GrayProfile()
I meant a parameterless one like cmsCreate_sRGBProfile().
Because I do not know how to transform the third file, file8.jp2:
-------------- ICC Profile[414] ---------------
cmmtype(0) version(2.32.0.0) class(scnr)
color-space(GRAY) profile-connection-space(XYZ )
date(23.1.2002) time(9:26:16)
signature(acsp) platform-signature()
profile-flags(0x1) [0]1 [1]0 [2:15]0
device-attr(0) white(0) negative(0) matte(0) transparent(0)
rendering-intent(0)
CIE: x(0.63190) y(1.0) z(0.54061)
[0]signature(desc) size[154]
Restricted ICC profile describing greyscale version of ROMM-RGB
[1]signature(cprt) size[42]
Copyright 2001 EKC-RICC Reference
[2]signature(wtpt) size[20]
XYZ(0.214, 0.214, 0.214)
[3]signature(kTRC) size[14]
curv size[1]
curv[0]gamma(1.205)
-----------------------------------------------
There is only one channel. I have no 'outprof'.
The two other images, using lcms-2.0, now look enchanting.
winfried
Und was machen Sie heute abend? Alles Events Ihrer Gegend auf einen Blick im
Arcor.de-Veranstaltungskalender: http://www.arcor.de/rd/footer.events
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